Good question. The riser blocks are available from Bingham Projects in the desert camo and the green mountain camo (in addition to the usual grey and brown actionwood), but their limb lams are strictly 'edge grain' and not that attractive to me compared to the diagonal flat grain that you're talking about. Should make for an exellent camo pattern on the limbs. The angle cut flat grain are not easy to find, but I did just notice that Ron Laclair's website for his shop states that they have them in both edge grain and flat grain, but not sure what their flat grain looks like.
I was recently able to talk one of the better known bowyers who makes bows with such lams into selling me two pair of each of the desert and green diagonal cut, but I asked it as a favor, as a repeat customer, and he was kind enough to sell me some from his supplies. He didn't reveal his source, but they're made for him specifically. You might try some of the materials suppliers listed above among the TG sponsors and in TBM. I guess we could also ask this question on the 'Bowyers Bench' forum.
BTW, I just glued up a longbow using the green mtn camo diagonal lams with a mix of grey actionwood inner limb cores with carbon and black glass inner lambs. The riser is a sandwich of grey actionwood around a middle 3/8" strip of the green mtn actionwood with black and white accents stripes in between and I think it's going to look pretty cool once the riser contours are cut.
Good luck finding them, I'd be interested in finding out if you do find a supplier.
Good luck
Curt